Resistive Touch Panel Distance Correction for Variable Contact Area
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Solution Overview
Problem
Existing touch panels experience deviations in distance measurements between two points due to varying contact areas, particularly when using inputs with different sizes such as pens and fingers.
Innovation Solution
A touch panel design with resistive films and electrodes, utilizing voltage measurements and correction units to calculate distances based on contact areas, correcting deviations by summing voltages from multiple directions and applying correction coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage measurement is performed to detect contact area, then measurement precision is improved, but device complexity increases due to multiple switches and voltage dividing resistors
Solution Approach 1:
The patent divides the voltage measurement process into multiple independent measurement phases, where different electrodes are activated in separate steps. This segmentation allows the system to measure contact area and calculate distance through a series of controlled voltage applications rather than requiring a single complex measurement system.
Solution Approach 2:
The patent performs preliminary voltage measurements to determine contact area before final distance calculation. By first measuring the contact area through voltage application to electrodes in different directions, the system prepares correction data that is then used to adjust the distance measurement, improving precision without requiring all measurements to occur simultaneously.
2Measurement precision
If correction mechanism is added to account for contact area variations, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the contact area measurement is used to correct the distance measurement. The control unit receives voltage measurement data, calculates contact area, and then uses this information to adjust the distance calculation, creating a feedback loop that continuously refines the measurement accuracy based on the actual contact conditions.
Solution Approach 2:
The patent changes the measurement parameters by measuring voltages in multiple directions (first direction and second direction perpendicular to it) and using different electrode configurations. By varying the measurement parameters across different measurement phases, the system obtains comprehensive data about both contact area and distance, enabling more accurate corrections.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses deviations in distance measurements between two points, ensuring accurate detection regardless of input size, by integrating a correction mechanism that accounts for varying contact areas.
Implementation Method 1
applying a voltage to the first resistive film via a first voltage dividing resistor, measuring a first direction voltage applied to the first resistive film in the first direction when the two points are pressed
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
A touch panel includes a first resistive film having a first electrode and a second electrode provided at both ends in a first direction, and a second resistive film having a third electrode and a fourth electrode provided at both ends in a second direction perpendicular to the first direction, the touch panel detecting contact between the first resistive film and the second resistive film caused by pressing the first resistive film, and outputting a pressed position. The touch panel includes a first detection unit that detects a contact area between the first resistive film and the second resistive film in pressing the first resistive film, a second detection unit that detects a distance between two points when the two points are pressed on the first resistive film, and a correction unit that corrects a detected distance between the two points in accordance with a detected contact area.